We newly introduce a compliant rim to realize hermetic sealing of electronic components at low temperature. The compliant rim easily deforms under pressing load owing to its cone-shaped cross section and, therefore, intermetallic bonding can be performed at low temperature. We demonstrate the room-temperature vacuum sealing using the compliant rim made of Au with the aid of ultrasonic vibration of submicron amplitude. A test vehicle fabricated using silicon and glass showed that the air leak rate of the room-temperature sealing was well below 1 × 10−12 Pa·m3/s, which is sufficiently low for use in vacuum packaging.

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Room temperature bonding technique using cone-shaped microbump with the aid of ultrasonic vibration is applied to fabrication of a near-infrared (NIR) image sensor. The image sensor is fabricated using chip-on-chip of InGaAs photodiode array on InP substrate and Si CMOS readout IC. The pixel pitch is 25 m to compose quarter-VGA class (320 × 256 pixels) resolution. A high quality imaging of heated object is demonstrated.

This paper reports that room-temperature bonding of LSI chips to metalization on a plastic film made of poly(ethylene naphthalate) (PEN) can be realized by ultrasonic bonding of a cone-shaped microbump made of Au. A 20-µm-pitch area array of cone-shaped Au microbumps was fabricated on a Si wafer by photolithography and electroplating. The counter electrode on the PEN film was composed of a Au (top)/Ni/Al (bottom) layered structure, where Ni and Au layers were deposited by electroless plating on Al interconnection. Bonding of 8,800 bump connections with 83.4 mΩ/bump has been achieved at room temperature.

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